If by “on top” you mean overlay other elements directly over the photobrowser, then, no, that is not possible. You can apply a caption to each of the images, of course, but the display of that caption is dictated by the f7 component itself.
All of the actionPhotoBrowserConfig settings are passed directly to the f7 component, OH does no additional configuration. So, whatever is available through the is what you’ve got. I’ve never spent too much time with the photos browser so I don’t know the details of its configuration. You’ll probably need to look through the f7 docs to answer this question fully.